Electric time system



June 8, 1937. J. w. BRYCE ELECTRIC TIME SYSTEM 2 Sheets-Sheet 1 Filed Oct. 24, 1932 INVENTOR- m E: BYW f- M ATTORNEY- June 8, 1937. J. w. BRYCE ECTRIC TIME SYSTEM Filed Oct. 24, 1932 2 Sheets-Sheet 2 ATTORN EY- Patented June 8, 1937 UNITED STATES PATENT OFFICE ELECTRIC TIlVIE SYSTEM James W. Bryce, Bloomfield, N. J., assignor, by mesne assignments, to International Business Machines Corporation, New York, N. Y., a corporation of New York Application October 24, 1932, Serial No. 639,180

10 Claims. (CI. 58-24) This invention relates to electric clock systems and more particularly relates to the provision of means for individually synchronizing or correcting secondary clocks of the synchronous motor drive type from a master clock.

Heretofore and generally in synchronously driven A. C. clock systems, no provision has been made for synchronizing the clocks. Generally reliance is placed on their being no suspension of current supply over the line circuit. Some systems have been provided wherein provision was made for effecting a group advance of a plurality of synchronously driven secondary clocks, and special secondary clocks have been provided with supplemental driving means,such as a spring mtor, to drive the same upon interruption of current flow. Secondary clocks, however, and particularly A. C. synchronously driven clocks are liable under some conditions of operation to drift and individually vary from true time and from each other. For example, if the current on an A. C. synchronous motor drive clock system is interrupted, the clocks do not all instantly stop. Some may coast ahead a greater distance than others to a stop position. Similarly, upon resumption of current flow the clocks do not instantly and all concurrently obtain full speed. Some may lag behind others according to the mechanical load and friction conditions which are dependent on many factors.

This invention comprises a simple and ingenions method of supervising a system of such clocks from a master clock independent of a system by which the clocks are normally operated and over the same lines, and furthermore, to supervise these clocks independently and individually so that any variation of individual clocks may be corrected.

The present invention has for its object the provision of an A. C. synchronously driven clock system and secondary clocks therefor wherein provision is made for individually synchronizing the A. C. synchronously driven clocks with respect to a master clock in contradistinction to group advancing a pluralityof such clocks or spring advancing individual clocks without regard to the relative time with respect to a master clock.

The invention has for a, further object the provision of an A. C. synchronously driven system, wherein the secondary clocks of the system are individually supervised with respect to a master clock. which may be readily adapted to old systems of the group supervised type without requiring wiring changes in the secondary clock circuits.

Another object is to provide a synchronized clock system in which a plurality of secondary clocks of the synchronous motor driven type are operated as independent units from the alternating current supply and are supervised and corrected by a master clock over the same line.

Further and other objects of the present invention will be hereinafter pointed out in the accompanying specification and claims and shown in the drawings which by way of illustration show one and a preferred embodiment of the invention.

In the drawings:

Fig. 1 shows a diagrammatic layout of the clock system with the supervising master clock.

Fig. 2 shows diagrammatically the essential parts of the secondary units together with the circuit. 1

The master clock in general detail may be oi any desired form, such as for example, is shown in the applicant's prior Patent No. 1,390,018.

Referring to Fig. l, the master clock includes the usual driving train adapted to drive the escape wheel 5 under control of the pendulum, operated verge 6 and its associated pendulum 1, which in the preferred embodiment is elected to be a sixty-beat pendulum controlling the escapement of an escape wheel which will make one revolution per minute. -On the shaft 8 on which the escape wheel is mounted is fixed a cam 53 which controls a pair of contacts ID to close them once each minute for a duration of from one to two seconds. Also fixed to the shaft 8 is a gear H which through a suitable train of reduction gears 42 rotates a shaft I3. on which is fixed'a cam l4, which rotates at the rate of one revolution in twenty-four hours.

The cam l4 controls the operation of the contacts l5, which are normally open, to close them for a period of a minute once every twenty-four hours, closing about thirty seconds beiore the even minute position of the -master clock and opening about thirty seconds after the minute position. In the preferred embodiment of the invention, the contacts ID and i5 may be arranged to both be closed at any suitable period during the twenty-four hours but for the sake of a detailed explanation of the present invention, it will be assumed that these contacts close about two seconds before twelve o'clock midnight and open exactly at midnight as synchronization will be affected at the opening of contacts I!) at the mid night hour. Contacts iii and i5 are wired in series with magnet I 6 of a relay so that when both of said contacts are closed, a circuit will be completed through one side of the alternating current power supply SS, through wire ll, contact 10, wire 18, contact I5, wire l9, magnet I6, wire 20, and back to the other side of the supply line. In the diagrammatic showing of the master clock in Fig. 1, the cams are shown in the position representing three or four seconds before twelve oclock midnight at which time the contact i 5 is already closed and the contact I0 is about to close.

When the magnet I6 is energized it attracts its armature 2|, thus opening the normally closed contacts 22 and 23 which operate in unison and open both sides of the supply-line SS thus breaking the current supply from the lines 24 and 25. Three secondaries are diagrammatically shown at X, Y and Z, the dotted lines representing a suitable casing that might enclose the mechanism shown therein. These secondaries comprise a motor having a field coil 26 and an armature rotor 27 fixed to a shaft 28 which drives through a suitable transmission gear box represented as 29 to rotate the shaft 30 at a rate of one revolution per minute. Fixed to the shaft 30 is a commutator 3i and a cam 32 cooperating with a cam follower 33 rotatably mounted on the end of a rocking lever 34 pivoted at 35. Pivot 35 may be suitably mounted to a suitable stationary support fixed to the casing on which the mechanism may be mounted.

The box-like representation 36 diagrammatically indicates a housing enclosing the mechanism shown in Fig. 2 comprising the cams 38, 39, 40, 4|, and 42 and their associated contacts, the relay 43, and the ratchet wheel 37 with its associated actuating mechanism.

At the "nd of the arm 34 opposite the cam follower 33 is pivotally mounted a pawl 44 held in coacting relationship with the teeth on the ratchet wheel 31 by the coil spring 44. Another pawl 45 is pivotally mounted on the armature lever 46 of the magnet 41 which is pivoted at 48 and biased in a clockwise direction by the spring 49. This pawl 45 also coacts with the teeth of the ratchet wheel 31; thus, the oscillation of either the lever 34 about its pivot 35 or the armature lever about its pivot 48 will rotate the ratchet in a clockwise direction. The customary retaining pawl 80 pivotally mounted at 8| is provided to prevent counterclockwise operation of the ratchet wheel 31 during the operation of the pawls 44 and 45. The cams 38, 39 and 40 are fixed to a common shaft 50 to which likewise is fixed the ratchet wheel 31 so that the rotation of the ratchet wheel likewise rotates these three cams at the same rate. Cam 42 is mounted on a common shaft 5| which is driven through suitable gearing (not shown) from the shaft 50 so that this cam makes one revolution in twenty-four hours.

As previously explained, the shaft 30 makes one revolution per minute and thereby oscillates the lever 34 from the high point to the low point of the cam once each minute, thus advancing the ratchet wheel 31 each minute for a distance equivalent to one tooth on the ratchet wheel. This ratchet wheel is provided with sixty teeth so that sixty oscillations of the lever 34 cause the wheel 31 to make one revolution which would be at the rate of one revolution per hour. The shaft 50 therefore may carry the minute hand 52 of the clock to indicate the time. The hour hand which is not shown will be operated in the customary manner by the usual dial works.

The commutator 3| which may be of any suitable conductive material is provided with insulating inserts 53 around the periphery and wiping on this commutator are two commutator brushes 54 and 55 set in relation to each other so that both brushes may contact with one of the commutator segments as it passes under the brushes, thus creating a circuit between the two.

Before tracing the circuit in the secondary clock shown in Fig. 2, it is necessary to understand the timing of the various cams and the timing of the operation of the contacts controlled thereby. Cams 38, 39 and 40 which are fixed to the same shaft that the ratchet wheel 31 is, will make one revolution per hour and the cam 42 will make one revolution in twenty-four hours as previously explained. These cams all control contacts in the same manner as contacts ID (Fig. 1) are controlled and as they are old in the art and have been illustrated in numerous other synchronized clock system patents, no further detailed description of the manner in which they open and close is deemed necessary. The timing of the contacts referred to in the description of the circuit of the secondary unit relates to the chronological-position of the secondary clock unit of which said contacts are a part. Contacts 58 are'controlled by the cam 38 so that said contacts open one minute before the hour position and close on the even hour, thus said contacts are normally closed for fifty-nine minutes, during the hour and open for only one minute. Contacts 59 which are controlled and operated by cams 39 are open at the hour position and close again at quarter past the hour. Contacts 60 which are controlled and operated by cam 40 close at twenty minutes before the hour and open two minutes later at eighteen minutes before the hour.

Contacts 62 which are controlled and operated by cams 42 are normally open and are closed for twenty-five minutes during one hour in twentyfour; i. e., they are closed for twenty minutes before the hour to five minutes past the hour, thus assuming that the synchronizing period is going to occur at midnight as previously explained, we would have the following schedule of operations of these five contacts with respect to the midnight hour. Contacts 58, normally closed, open at 11: 59 P. M. and close at 12 midnight. Contacts 59 normally closed, open exactly at 12 midnight and close at 12:15 A. M. Contacts 60 normally open, close at 11: 40 P. M. and open at 11: 42 P. M. Contacts 62 normally open, are closed at 11: 40 P. M. and open at 12: 05 A. M.

With the above mentioned" schedule in mind,

the circuit will now be traced and the operation of the secondary clock explained assuming that the time under consideration is shortly before the synchronizing period. In Fig. 2, the current will flow from line 25, through wire 64, coil 26 of the motor, line 65, contacts 58 now closed, wire 66, and back to line 24. The synchronous motor is therefore in operation. As the clock reaches the chronological position of 11: 40, contacts 60 will close and current will flow from line 25, through coil 43, wire 61, contacts 60, wire 68, wire 69, contacts 62, which also closed at 11': 40 per schedule, wire 10, wire H and back to line 24. This will cause relay magnets 43 to become energized and to attract its armature, thus lifting contact blades 12, I3 and 74, closing contacts 15 and opening contacts '16 and H. The closure 'of contacts 15 causes a stick circuit to be set up to the magnet 43, thus causing said magnet to remain energized in spite of the fact that the contacts 60 remain closed for only two minutes.

The stick circuit is as follows: from one side of the line 25, magnet coil 43, contact blade 12, contacts 15 now closed and back to the other side of the line 24. Thus, the motor will continue to operate advancing the ratchet wheel 31 at its normal rate and rotating the commutator 3|. Inasmuch as contact 16 is now opened by virtue of the energization of magnet 43, impulses from the commutator 3| will not effect the magnets 41, even though contacts 59 and 62 may close.

The clock will continue, therefore, to move forward driven by the synchronous motor at its normal rate until it reaches 11: 59 P. M., at which time, according to the schedule, contacts 58 open for one minute; i. e., it will. open for one minute asindicated chronologically on the clock in question, being open only between the time when the as follows:

clock reaches 59 until it advances to the sixtieth minute. If the clock reaches this fifty-ninth minute, in advance of the correct time, it will, of course, be fast so that more than one minute will actually elapse' between the closing and the opening of contacts 58. As explained, the contacts-58 now open and the motor stops and therefore the rotation of the cam 38 has stopped. The resumption of operation of the motor occurs At two seconds before twelve, midnight, contacts ID in the master clock (Fig. 1) will close, contacts l5 having previously closed, and relay magnets [6 will become energized through the following circuit: from one side of the power supply line SS, through line 20, magnet l6, line I9, contact I5, line l8, contact l0, line H, and back to-the other side of the power supply line. The energization of the magnet I6 will cause it to lift its armature 2|, thus opening contacts 22 and 23, which open the circuit to the supply line 24 and 25. The opening of this circuit causes the magnet 43 (Fig. 2) to become deenergized and allow the contact blades 12, 13, and 14 to drop under the influence of the spring 82, thus opening contacts 75 and closing contacts 16 and 71. Contacts 10 in the master clock now open again at exactly twelve midnight, cause relay i6 to become deenerglzed, permitting contacts 22 and 23 to close and thus again impressing the power supply up lines 24 and 25.

Upon the resumption of the power supply to these lines, the synchronous motors in the clocks resume operation-through the circuit from the supply 25, line 64, motor field coil 26, lines 65 and 18, contact 11 (now closed) line II, to the supply line 24. It will thus be seen that if the secondary clock is fast, it wilhreach the fiftyninth minute chronological position as indicated by that clock and the contacts 58 will open stopping further operation of the clock until the master clock reaches the midnight hour position, at which time the motor will resume operation. At the time the master clock deenergizes the supply line and later restores it, after an interruption of approximately two seconds, it being at midnight, it will be observed that the secondaryclock was stopped at its fifty-ninth minute position and released at that time, so that would start a minute slow. The resumption of the operation of the motor starts the commutator 3| rotating so that magnets 41 receive an impulse advancing the ratchet wheel immediately one tooth, to the twelve oclock position, at which time contacts 59 open so that only one impulse is transmitted from the commutator. This is effected in the following manner: Contacts 62 close at the same time that contacts 60 close and energize the magnet 43 thereby opening contacts 16 to break the circuit through the contacts 62 and the contacts 59 which were already closed, thus holding open the circuit from the commutator brushes 54 and 55 through the magnet 41. When, therefore, contacts 16 close at midnight by virtue of the control of the master clock, a circuit is completed from part of the line 25, through wires 64, commutator contacts 54 and 55, relay contact 16, wire 19, relay magnet coil 41, wire 80, contacts 59 (now closed), wire 69, contacts 62 (now closed), wire I0, wire H and back to the supply line 24. When the magnet 47 receives the impulse it is energized, attracting its armature 46 and upon the break of said impulse the armature is released and through thecoaction of the pawl 45 with the ratchet wheel 31 and the biasing spring 49 said ratchet wheel is advanced one step, advancing the clock to the chronological position of midnight, at which time contacts 59 open as shown by the time schedule, and prevent any more impulses from being transmitted to the magnet 41. The clock now resumes its step by step advance under the control of the synchronous motor.

Let it now be assumed that the clock is 15 minutes slow when the hour for synchronization approaches, Contact 60 closes at 11:40 as shown by the chronologicalposition of the slow clock, the true or correct time actually being 11:55. Relay magnet 43 is energized as previously explained but the motor does not stop as contact 58 has not yet opened. At two seconds before midnight the master clock contact causes the power to be out off of the supply lines 24 and 25 which deenergizes magnet 43, the power being again restored to the supply lines 24 and 25 at exactly 12:00 o'clock true time, all of which has also been previously described. At this time it will be understood that the chronological position of the slow clock will show 11:45, it being 15 minutes slow. Contact 59 and also contact 62 will be closed therefore in accordance with the schedule set forth. When the current is restored then at 12:00 oclock a circuit is completed and the motor will start to operate through the circuit from line 25, wire 64, coil 26 of the motor, wires 65 and 18, contact 11, wire H and back to the other side of the line 24. The commutator 3| will therefore rotate and send out rapid impulses over the following circuit: from supply line 25, through wire 64, commutator brushes 54 and 55, relay contact 16, wire 19, magnet 41, wire 80, contact 59 (now closed), wire 69, contact 62, (now closed) wires 10 and II back to the other side of the supply line 24. The rapid impulses will energize magnet 49 in rapid succession causing the pawl 45 to reciprocate against the ratchet wheel 31 thus advancing the clock. The 15 impulses required'to bring it to the 12:00 oclock position will occur in less than a minute and when said clock reaches the 12:00 oclock position contact 59 will open and cut off the rapid impulses and the clock will be in a position to step ahead to 12:01 in its usual manner.

The master clock is preferably a very high grade timepiece fully compensated against temperature changes and the only function of this timepiece is to open and close the main circuit at midnight to control the synchronous motor driven clocks as previously described.

Although the preferred embodiment shows a complete breaking of the current supply in the main line circuit, it will be understood that the master clock contacts could be arrangedreadily to control resistor units in series with the line or the operation of a transformer to merely lower the voltage on the supply line, instead of completely opening the circuit. In the latter event, the magnet coil 43 would be carefully balanced so that it would be properly energized at the normal supplied current, but would become deenergized upon a suitable drop in voltage. This latter expedient could be used readily where there was no time during the twenty-four hours that the user of such a system would care to have his power supply completely shut off for an instant of one or two seconds. In such a case, a momentary dropping of the voltage would merely cause a dimming in the light circuit from which the clock would be operating.

While the supplemental novel features of the invention as applied toa single modification, has been shown and described and pointed out, it will be understood that various omissions and substitutes and changes in the form and details of the device illustrated, and in its operation may be made by those skilled in the art without departing from the spirit of the invention. I intend to be limited, therefore, only as indicated by the Scope of the following claims:

What is claimed is:

l. A clock system comprising a line circuit foltransmitting alternating current adapted for power and lighting purposes, a plurality of selfstarting synchronous motor driven secondary clocks connected to said line circuit, a master clock including means for controlling said circuit to periodically interrupt transmission of alternating current in said circuit, means in each secondary clock for periodically suspending operation of the secondary clocks, and means operable upon said periodic interruption of the current in the line circuit by said master clock control means for resuming operation of the secondary clocks.

2. A clock system comprising a plurality of self-starting synchronous motor driven secondary clocks connected to a network transmitting alternating current for lighting and power purposes, a master clock including means operable to effect a periodic suspension of transmission of said current over said network, synchronizing means in each secondary clock operable in conjunction with the master clock control for periodically effecting synchronization of each secondary clock with respect to the master clock, said means including means controlled by the chronological condition of a secondary clock for suspending operation of its synchronous motor when said clock is fast with respect to the master clock, means operable upon suspension of transmission of current through the network under control of the master clock for conditioning said synchronous motor for resumption of operation, and for conditioning said clock that is slow with respect to the master clock to be rapidly advanced upon resumption of transmission of current in the network, and means operable under control of the synchronous motor for effecting a rapid advance of said clock that is slow into synchronism with the master clock upon resumption of the current transmission and the operation of the motor.

3. A clock system comprising an A. C. line circuit, a plurality of self-starting synchronous motor driven secondary clocks connected, to said line circuit, a distant master clock providing a control upon said line circuit and synchronizing means in each individual secondary clock controlled by the conjoint chronological condition of each individual secondary clock with respect to the distant master clock for individually, periodically synchronizing each individual secondary clock with respect to the distant master clock, wherein the synchronizing means in each secondary clock comprises means for periodically, temporarily suspending the synchronous motor drive of each clock where it is fast or on time, with means for suspending the synchronous motor drive for an on time secondary clock by a fixed time amount, and means for suspending the synchronous motor drive for a fast clock by a time amount determined by the time amount that the fast clock is fast with respect to the master clock,

means for providing a supplemental advance of each clock and for automatically re-initiating the synchronous motor drive thereof, said last mentioned means including-provisions for imparting supplemental drive of a, fixed amount to an on time and to a fast secondary clock and for imparting supplemental drive to a slow clock by an amount related to the amount that the clock is slow with respect to the master clock.

4. In a clock system including a plurality of alternating current synchronously driven secondary clocks and a master clock for periodically controlling synchronization of said secondary clocks with respect to said master clock and including in combination a self-starting synchronous motor in each secondary clock for advancing said clock at a normal rate, means controlled by the chronological position of each clock for suspending operation of the motor to interrupt'the advance of the clock, means controlled by the mas ter clock for resuming operation of said motor, and means controlled by the chronological position of each secondary clock for effecting advance of said clocks under control of said motor at a rate more rapid than normal if said secondary clock is slow and after the operation of the motor has been resumed.

5. In a clock system including a plurality of alternating current synchronously driven secondary clocks and a master clock for periodically controlling synchronization of said secondary clocks with respect to said master clock and including in combination a self-starting synchronous motor in each secondary clock, means controlled by said motor for effecting a periodic advance of said secondary clock at a normal rate, means controlled by the-chronological position of said secondary clock for suspending operation of said motor to interrupt the advance of said clocks, means controlled by the master clock for resuming operation of said motor, and supplemental means controlled by said motor for advancing said secondary clock at a rate faster than normal if said secondary clock is slow and upon resumption of operation of said motor.

6. In a clock system, including a plurality of alternating current synchronously driven secondary clocks having means adapted to effect an impulse advance of each secondary clock and including in combination a master clock, means in each secondary clock operative under chronological control from the master clock for individually synchronizing each secondary clock in accordance with its relative, chronological condition as compared with the master clock, wherein the synchronizing means include means for periodically suspending synchronous alternating current advance of an on-time secondary clock wherein resumption of A. C. synchronous advance calls into operation means adapted to effect an impulse advance of the secondary clock to bring the latter into synchronization with the master clock.

7. In a clock system, including a plurality of alternating current synchronously driven secondary clocks having means adapted to effect an impulse advance of each secondary clock and including in combination a master clock, means in each secondary clock operative under chronological control from the master clock for individually synchronizing each secondary clock in accordance with its relative, chronological condition as compared with the master clock, wherein the synchronizing means include means for periodically suspending synchronous alternating current advance of a fast secondary clock and wherein resumption of A. C. synchronous advance calls into operation .means adapted to effect an impulse advance of the secondary clock to bring the latter into synchronization with the master clock.

8. A clock system, including alternating current supply lines for a plurality of secondary clocks, a master clock, a plurality of synchronously-driven secondary clocks driven by and receiving alternating current from said line, means in the master clock for periodically suspending and then resuming supply of alternating current to the said clock over said line, and means in each secondary clock controlled by the suspension and resumption of alternating current flow thereto over said line, and in conjoint accordance with the chronological condition of each individual secondary clock for individually synchronizing each secondary clock with the master clock.

9. A secondary clock for use in alternating current-operated clock systems comprising time indicating means, a synchronous motor for driving the same, means for advancing the time indicating means step-by-step under control of the synchronous motor and supplemental means controlled by the operation of said synchronous motor for advancing said time indicating means step-by-step at a rate faster than normal.

10. in a clock system including 'a plurality of alternating current synchronously driven secondary clocks and a master clock for periodically controlling synchronization of said secondary clocks with respect to said master clock and including in combination a self-starting synchronous motor in each secondary clock, means controlled by said motor for effecting a periodic advance of said secondary clock at a normal rate, means controlled by the master clock and at a certain chronological time thereof for suspending operation of said motor for a predetermined timed interval when said secondary clocks are slow with respect to the master clock, and supplemental means operable by said motor upon resumption of operation at the termination of said predetermined time interval for effecting a periodic advance of said secondary clock at a rate faster than normal.

JAMES W. BRYCE. 

